Water screen



c. A. BRANDT WATER SCREEN Filed Oct. 24, 1925 251199125-51'168t 1 g I Car/ALB/"andf INVENTOR- ATTORNEY.

July 10, 1928. 1,676,245

c. A. BRANDT WATER SCREEN Filed Oct. 24, 1925 2 Sheets-Sheet Car/ABra/vdf INVENTOR BY ATTORNEYS.

Patented July 10, 1928.

UNITED STATES CARL A. BRANDT, OF GREAT NECK, NEW YORK.

WATER SCREEN.

I Application filed. October 24, 1925. Serial No. 64,623.

My invention relates to steam boilers and has particular reference to the construction of waterscreens for lining the furnace and combustion chamber walls as a protection against excessive temperatures and for increasing the evaporative capacity and efliciency of the boiler.

The use in modern boiler plants of fuel oil and pulverized coal for firing large bpiler units at high combustion rates, has resiilted in furnace temperatures which make it highly desirable that the refractory furnace wall surfaces be protected by some form of water-cooled surface. This also holds true to a lesser extent in the case of stoker-fired boilers. A number of different types of Water screens have been proposed for the purpose of protecting the furnace walls of the various types of furnaces.

In order properly to perform their function as a protecting means, such screens should present to the combustion gases as nearly an unbroken Water-cooled surface as possible, and in the screens heretofore proposed, which take the form of a plurality of parallel tubes joined by inlet and outlet headers, the close spacing of the tubes desired has been obtainable only by staggering the tube ends, because of the distance necessary between the tube holes in the header, in order to insure sufficient ligament strength in the latter. This construction is undesirable, as it necessitates the use either of headers of Very large sectional area, or of double headers. Moreover, because of the severe temperature conditions to which such screens are subjected, it is desirable that the minimum number of joints be used in the screen structure.

In some cases the joints within the setting may be eliminated by carrying the individual screen tubes through the furnace walls to outside headers, but in order to re-- duce the possibilityof air leakage incurred by a large number of tubes passing thru the Walls at a point where expansion stresses are severe, it is generally most desirable to place both tubes and headers within the setting. It is the object of my invention. therefore, to provide a water screen which will present a substantially unbroken water-cooled surface, composed of a plurality of integral tubular units which may be connected as desired into any form ofboiler and the end portionsof which may be in spaced relation in a single plane when the tubular portions of such units are substantially contacting. A further object of the invention is the provision of ascreen structure composed of a plurality of tubular units, connected into headers or equivalent elements, inwhich the number of joints between'the tubes and the elements to which they may be connected is reduced to a number such'that the total number of joints necessary does not exceed the number of tubes used. Astill further object of the invention is the provision of a Water screen structure which is capable of with-- standing the extreme temperature conditions existing in a boiler furnace and which may be placed entirely therein, so thatthe number of connections extending through the furnace walls may be reduced to a minimum; that is, limitedto the inlet and outlet connections, or, if desired, connected into the circulating system wholly within the setting. Other and more detailed objects of the invention will appear in connection with the following description of an illustrative embodiment of the invention as applied to a boiler of the general type disclosed in my copendmg application, Serial No. 747,032, filed October 31st, 1924. i

In the accompanying drawings, Fig. 1 is a .central vertical longitudinal section taken through a boiler. of this type mounted in a setting adapted for firing by fuel oil,-and' Fig. 2 is a section taken on the line 2-2 of Fig. 1.

Referring now to Fig. 1, the boiler illustrated resembles the conventional form of cross-drum water tube boiler and comprises the main steam and waterdrum 1 and a bank of horizontally inclined steam-generating tubes 2, arranged in two triangularly shaped banks over a central combustion chamber, the latter having an A-shaped roof formed by the tube banks, as is more clearly shown in Fig. 2. At their upper ends the generating tubes 2 are connected into vertical upflow headers 3, the lower ends of which are placed at progressively higher levels as the longitudinal center line of the boiler is approached. The headers 3 are connected by nipples 4 to a common transverse header 5, which is in turn connected to the steam and water drum 1 by the circulators 6. The lower ends of the generating tubes 2 are connected into a series of vertical downflow headers 7, similar in arrangement tothe headers 3, the headers 7 being supplied with water from drum 1 by means of nipples 8.

The roof of the boiler is formed by a series of tiles 9 supported on the upper rows of tubes and sloping upwardly from each side The sets of nipples 4 and 8 are increased in refractory tile to form gastight walls above the level of the headers 3 and 7, and refractory side walls are provided which terminate at their upper ends at a point below the level of the roof tiles 9. An outer casing 15 is, provided which extends, upwardly to the top of the boiler and terminates in the breeching 16. The side walls of the outer casing 15, extending upwardly beyond the inner walls 13 and 14, provide passage-ways 17 and 18, extending the full longitudinal length of the-boiler (see Fig. 2) connecting the steam generating and economizer banks with the breeching for the exit of the combustion gases.

It is to be understood, however, that thepresent invention which is concerned with the protection of the furnace and combustion chamber walls, is not to be limited to application with this form of boiler, but may be equally well applied to any desired form.

In the furnace chosen for illustration, oil burners 19 and 20 are provided in the front and rear furnace walls respectively, and the side walls 13 and 14 of the furnace are each protected above the level ofburners by a water screen embodying the present invention. The side wall screens are each coniposed of a number 'of' integral tubular units, each of which is formed by a plurality of tubes 21, which at their ends are merged into a single tubular end portion 22, having a cross-sectional area substantially equal to that of all the tubes in the unit and a diameter substantially smaller than the width of the unit intermediate the end portions. The circular end portions 22 of the units which join the circular pipe portions may be formed integrally )y the forging process described in Patent 0. 1.155,110, issued to C. H. True and N. T. McKee andthe end of the portion 22 brought down to the desired diameter by the process described in Patent No. 1,255,355 issued to C. H. True and C. A. Brandt. The units are formed with the tubes 21 in substantially contacting relation and the screen is formed by a plurality of units placed in close juxtaposition, so that a substantially unbroken water wall is provided, lining and protecting the.

cal headers 25 corresponding to the upperheaders 23, and water is supplied through the downflow pipes 26, which are connected into headers 25 at points 26 and 26".

In the embodiment shown, due to the use of oil burners, the boiler setting is comparatively low, which results in the furnaceside walls being greater in length than in height. For this reason the units forming the water screen are placed longitudinally, as in this position the screen may be formed of a comparatively small number of long units,

which is desirable because of the small number of joints required. It will be obvious. however, that thls' particular disposition of the side wall units need not be adhered to and that they may be placed at any desired angle to the horizontal. The most desirable disposition of the units is that which requires the minimum number of units for the protection of a-given'wall area and in the case of a pulverized fuel installation, having ahigh and comparatively narrow furnace, this condition would best be met by placing the units vertically rather than in a horizontal or inclined position.

The front wall 27 of the boiler setting,

below the level of the headers 3, is protected by a screen' formed of units similar to those employed in the construction of the side wall screens. The front wall units are formed of tubes '28 joined at their ends to form single integral end portions 29, and in this instance the units are placed vertically in closely spaced relation with their lower ends entering a common transverse header 30 and their upper ends entering the lower-ends of the corresponding upflow headers 3, into which they discharge. Water is supplied to the front wall screen by means of the'pipes 31, which connect into the downflow pipes 26, supplying theside wall screens.

As shown in Fig. 2, header 30 is provided with hand holeopenings and covers 30 opposite the unit ends 29, for the purpose of inserting cleaning tools into the units, and the headers 23 and 25 of the side wall screens are similarly equipped. Inasmuch as the screen tubes have a very high evaporative rate, the tendency to form scale therein is pronounced, and because of the severe temperatures-to which they aresubjected it is imperative that they may be readily cleaned ofscale accumulations. In this connection 1t 1s particularly to be noted that the form of the unit end portions 22 and29 permits the easy insertion of a cleaning tool into any of the tubes in the unit;

The rear wall of the furnace proper is built up of refractory material 32 and the 1 rear wall between the furnace setting and the headers 7 is formed and made gas-tight by means of nipples 33 extending from the bottom" of the headers 7 to a common trans- 10 verse header 34, and which are encased in refractory packing 35. i

It will be readily apparent from the preceding description that .I have provided by my invention a form of 'water screen in which .the maxi mum amount of screening surface maybe obtained in the form best adapted towithstand high p'ressuresthat is, tubularand" with the minimum numher of joints exposed to the high temperatures of the boiler furnace. It will further be apparent that by my invention, I am able to place water screen tubes in substantially contacting arrangement and at the same time rovide sufficient space between the tube ho es required in the headers to insure a sufficient ligament strength in the latter. While in the present embodiment I have shown the tubular portion of the units arranged in a single plane parallel to the wall surface, it will be obvious that the individual units may be turned about. their longitudinal axes to any degree desired, so that either a row of staggered tubes or a double row of tubesmay be interposed between the furnacewalland thecombustion chamber. It will further be obvious that the number of individual tubes per unit need not be limited to two but may be increased by the process described Patent No. 40 1,264,455 issued to C..H. True, as, for example, to groups of three which maybe arranged in alined relation, .or, in case it is desired to provide more cooling surface between the wall and the combustionchamber than can be provided with a single row of tubes, may be arranged in triangularrelation. i

It is further to be understood that while I have described a'p'articular arrangement of waterscreen adapted to a particular boiler, the invention "is not to be limited by the location of the screen nor the manner in which it is connected into the boiler system,

as it is readily applicable to substantially all forms of combustion chambers and, moreover, need not be connected into the boiler circulating system in case it is desired to supply it with water from some other source. -Iclaimz 1. A water screen comprising a plurality of water tubes circular in cross section and arranged in closely spaced parallel relation to form a substantially unbroken water wall, said tubes bein divided into groups with 65. the tubes of eac group integrally joined at greater than the' diameter of either end portheir ends to form units having single tubular end portions, the width oi the tube group of each unit being greater than the diameter of either end portion of the unit and the internal cross-sectional area of 'each end portion being .not less than the total internal cross-sectional area of the corresponding tube group, and means formino' part of a water j circulating system to which the end portions of said units arecomiected. I

2. A water screen comprising a plurality of water tubes circular in cross-section and arranged in closely spaced parallel relation to form a substantially unbroken water wall, said tubes being divided into groups of two tubes each with the tubes of each group integrally joined at their ends to form units having single tubular end portions, the width of the tube group of each unit being tion of the unit, and the'internal cross sec: tional area .of each end portion being not less than the total internal cross-sectional area of the corresponding tube group, and meansforming part of a water circulating system to which the end portions of said units are connected.

3. A water screen comprising a pluralityof water tubes circular in cross-section and arranged in the same plane in closely spaced parallel relation to form a substant1ally unroken water wall, said tubes being divlded into groups with. the tubes of each group Y integrally joined at their ends to form units having single tubular end portion-s, the width of the tube group of each unit being greater than the diameterof either end portion of the unit and the internal cross sectional'ara of each end portion being not less than the total internal cross-sectional area of the corresponding tube group, and means forming part of a water circulating system to which i the end portions of said units are connected.

4. A water screencomprising aplurality of water tubes circular in cross-section and arranged in the same plane in closelyspaced. arallel relation to form a substantially un-' roken water wall, said tubes being divided" into groups of two tubes each with the tubes of each group integrally jolned at theirends to form units having single tubular end portions, the width of the tube grou of' each unit being greater than the meter of either end portion of the unit and the internal cross sectional area of each end portion being not less than the totalinternal cross-sectional area of the corresponding tube group, and means forming part of a water circulating system to which the end portions of said units are'connected.

5. A water screen comprising a plurality of water tubes circular in cross-section and arranged in closely spaced parallel relation to form a substantially unbroken water wall, said .tubes being divided into groups with 130 the tubes of each group integrally joined v tional area of each end portion being not,

at their "ends to form units having single tubular end portions, the width of the tube group of each unit being greater than the diameter of either end portion of the unit and the internal cross sectional area of each end portion being not less than the total internal cross-sectional area of the corresponding tube group, and headers forming part of a water c-irculating'system to which the end portions of said units are connected.

6. A water screen comprising a plurality of verticalwater tubes circular in crosssection and arranged in closely spaced parallel relation to form a substantially unbroken water wall, said tubes being divided into groups with the tubes of each group integrally joined'at their ends to form units having single tubular end portions, the width of-the tube group ofeach unit being greater than the diameter of each end portion of the unit and the internal cross secless, than the total internal cross-sectional 'area of the corresponding tube group, and

means forming part of a water circulating system to which the end. portions of said units are, connected.

7. A water screen comprising a plurality of water tubes circular in cross-section and arranged in closely spaced parallel relation to form a substantially unbroken water wall, said tubes being divided into groups of two tubes each with the tubes of each group integrally joined at their ends to form units having single tubular end portions, the width. of the tube group of each unit be ing greater than the diameter of either end portion of the unit, and the internal crosssectional area of each end portion being substantially greater than the internal cross-sectional area of each tube associated therewith, and means forming part of a water circulating system to which the end portions of said units are connected. 7

thetubes of each group integrally joinedat their ends to form units having single tubular end portions, the. width of the tube group of each unit being greater than the diameter of either end portion of the unit, and the internal cross-sectional area of each end portion being substantially greater than half the internal cross-sectional area of the tubes associated therewith, and means form ing part of a water circulating system to which the end portions of said units are con nected.v

9. A water screen comprising a plurality of water tubes circular in cross-section and arranged in closely spaced parallel relation to form a substantially unbroken water wall, said tubes being divided into groups with the tubes of each group integrally joined at their ends to form units having single tubular endportions, the width of the tube group of each unit being greater than the diameter of either end portion of the unit,

means forming part of a water circulating system to which the end portions of said units are connected,the-internal cross-sectional area of'each end portion intaking from the water circulating system being substantially greater than half the internal crosssectlilonal area of the tubes associated therew1t I CARL A. BRANDT. 

